CVE-2026-61741: HTTP4S HTTP4S-Scala-XML

Critical severity, CVSS 9.3. EPSS: 0.3% chance of exploitation in the next 30 days.

http4s-scala-xml provides `EntityDecoder[F, scala.xml.Elem]` instances that parse XML message bodies. Prior to versions 0.24.1 and 1.0.0-M39, these decoders used a `javax.xml.parsers.SAXParserFactory` obtained from `SAXParserFactory.newInstance` without any security configuration. With the JDK's default settings, the parser resolves DOCTYPE declarations, external general and parameter entities, and external DTDs.An application that uses these decoders to parse untrusted XML is vulnerable to XML External Entity (XXE) attacks. An attacker can craft a request that discloses local files readable by the service process, performs server-side request forgery (SSRF) against internal network resources, and/or causes denial of service through entity expansion. Versions 0.24.1 and 1.0.0-M39 fix the issue.

Affected products

• HTTP4S HTTP4S-Scala-XML: before 0.24.1 (fixed in 0.24.1); from 1.0.0-M1, before 1.0.0-M39 (fixed in 1.0.0-M39)

Published 2026-09-24. Last modified 2026-09-30.